Field of the Invention
The present invention relates generally to switches and more specifically to membrane-actuated miniature switch assemblies.
The trend of most modern electronic devices is to reduce both the size and the cost of the components and the device as a whole. As such, even the most rudimentary elements must undergo a physical redesign to account for this trend. In addition to attempting to reduce the size of these components, there is also a desire to minimize their obtrusiveness in any particular device. Bulky knobs and switches are often unpleasant to the eye and may not even be functional in certain environments. Finally, switches used in many commercial applications are often repeatably and forcibly engaged. That is, the switches are subjected to abusive usage, which eventually leads to damage. Thus, there is a desire to provide a switch which can withstand this type of use over a relatively long period of time.
In recognition of the above attributes, membrane switches were developed and have become quite common. In general, a membrane switch comprises a pliable membrane, usually having two layers. The upper layer usually will have a metal plate or some other type of electrical contact in it. When the top layer is depressed, it contacts the lower layer and the electrical contact bridges the ends of various terminals embedded in the lower layer thus closing or actuating the switch.
There exists a need to provide a membrane switch capable of carrying high current loads, thus reducing the overall size and complexity of various electronic devices. Due to the nature and the physical dimensions of the present membrane switches, they are prohibited from carrying large current loads. Consequently, these are not well suited to those applications which carry large currents. As such, if the switch activates a device which requires a large current load the membrane switch must act as an initial switch and a secondary or booster switch must be incorporated into the device. When so used, the membrane switch actuates the booster switch, and the booster switch engages the electronic device. This increases the number of components required to make the electronic device thus increasing the cost and complexity of it.